/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.coders;



import com.bff.gaia.unified.sdk.util.ExposedByteArrayOutputStream;

import com.bff.gaia.unified.sdk.util.StreamUtils;

import com.bff.gaia.unified.sdk.util.VarInt;

import com.bff.gaia.unified.sdk.values.TypeDescriptor;

import com.bff.gaia.unified.vendor.guava.com.google.common.io.ByteStreams;



import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;



/**

 * A {@link Coder} for {@code byte[]}.

 *

 * <p>The encoding format is as follows:

 *

 * <ul>

 *   <li>If in a non-nested context (the {@code byte[]} is the only value in the stream), the bytes

 *       are read/written directly.

 *   <li>If in a nested context, the bytes are prefixed with the length of the array, encoded via a

 *       {@link VarIntCoder}.

 * </ul>

 */

public class ByteArrayCoder extends AtomicCoder<byte[]> {



  public static ByteArrayCoder of() {

    return INSTANCE;

  }



  /////////////////////////////////////////////////////////////////////////////



  private static final ByteArrayCoder INSTANCE = new ByteArrayCoder();

  private static final TypeDescriptor<byte[]> TYPE_DESCRIPTOR = new TypeDescriptor<byte[]>() {};



  private ByteArrayCoder() {}



  @Override

  public void encode(byte[] value, OutputStream outStream) throws IOException, CoderException {

    encode(value, outStream, Context.NESTED);

  }



  @Override

  public void encode(byte[] value, OutputStream outStream, Context context)

      throws IOException, CoderException {

    if (value == null) {

      throw new CoderException("cannot encode a null byte[]");

    }

    if (!context.isWholeStream) {

      VarInt.encode(value.length, outStream);

      outStream.write(value);

    } else {

      outStream.write(value);

    }

  }



  /**

   * Encodes the provided {@code value} with the identical encoding to {@link #encode}, but with

   * optimizations that take ownership of the value.

   *

   * <p>Once passed to this method, {@code value} should never be observed or mutated again.

   */

  public void encodeAndOwn(byte[] value, OutputStream outStream, Context context)

      throws IOException, CoderException {

    if (!context.isWholeStream) {

      VarInt.encode(value.length, outStream);

      outStream.write(value);

    } else {

      if (outStream instanceof ExposedByteArrayOutputStream) {

        ((ExposedByteArrayOutputStream) outStream).writeAndOwn(value);

      } else {

        outStream.write(value);

      }

    }

  }



  @Override

  public byte[] decode(InputStream inStream) throws IOException, CoderException {

    return decode(inStream, Context.NESTED);

  }



  @Override

  public byte[] decode(InputStream inStream, Context context) throws IOException, CoderException {

    if (context.isWholeStream) {

      return StreamUtils.getBytesWithoutClosing(inStream);

    } else {

      int length = VarInt.decodeInt(inStream);

      if (length < 0) {

        throw new IOException("invalid length " + length);

      }

      byte[] value = new byte[length];

      ByteStreams.readFully(inStream, value);

      return value;

    }

  }



  @Override

  public void verifyDeterministic() {}



  /**

   * {@inheritDoc}

   *

   * @return objects that are equal if the two arrays contain the same bytes.

   */

  @Override

  public Object structuralValue(byte[] value) {

    return new StructuralByteArray(value);

  }



  /**

   * {@inheritDoc}

   *

   * @return {@code true} since {@link #getEncodedElementByteSize} runs in constant time using the

   *     {@code length} of the provided array.

   */

  @Override

  public boolean isRegisterByteSizeObserverCheap(byte[] value) {

    return true;

  }



  @Override

  public TypeDescriptor<byte[]> getEncodedTypeDescriptor() {

    return TYPE_DESCRIPTOR;

  }



  @Override

  protected long getEncodedElementByteSize(byte[] value) throws Exception {

    if (value == null) {

      throw new CoderException("cannot encode a null byte[]");

    }

    return (long) VarInt.getLength(value.length) + value.length;

  }

}